Design Architect: Skidmore, Owings & Merrill LLP (SOM)
Architect of Record: Corgan Associates, Inc.
Structural Engineer: L.A. Fuess Partners, Inc.
Construction Manager: McCarthy Building Companies, Inc.
Total Project Cost: $32 million
Total Project Size: 59,000 sq ft (phase one)
Award: 2013 CRSI Award Winner – Cultural & Entertainment Facilities Category
Photography: Hedrich Blessing Photographers, Chicago, IL
Aerial Photography, Inc.
STRUCTURAL FRAMING SYSTEM
The Performance Hall is essentially a two-level structure, with variable floor-to-floor heights, constructed atop a subterranean parking garage. The most prominent structural feature was the cast-in-place, load-bearing concrete walls that were used throughout the structure. These walls surrounded the performance hall itself, including all the stage walls; also the perimeter walls and all internal walls along the major hallways. The wall surfaces are exposed as the architectural finish.
The ground floor structures vary in system primarily because of the parking garage structure below. The Hall seating floor is a two-way flat slab over crawlspace. The lobby floor is concrete on metal deck supported by CMU pony walls that bear on the parking structure below. The stage floor is a pan formed concrete joist system over a crawlspace, and the back of house structure is a concrete topping slab supported directly on the garage structure.
Upper level structures generally utilize a formed beam and slab system, with a pan formed joist system at the mechanical level. Cantilevers are used at several locations in order to provide desired column-free areas: at the balcony framing, the lobby framing and the feature lobby stair. The stage roof includes a thick layer of concrete topping for acoustical purposes.
As with any performance hall project, acoustics drive many design decisions. Acoustics were particularly crucial on this project, as this building is not only subjected to normal urban noise, but has a parking garage directly underneath it, and is right in the normal airline flight path of Love Field. Airborne noise and structure-born noise, as well as vibration from the parking garage below were a particular concern. Concrete framing was used in a number of different ways to meet the acoustic requirements for the project.
OTHER KEY ELEMENTS:
- Sound management within the Hall itself is managed partially through the use of “articulated board formed” concrete walls. The rear and side walls of the Hall, all architecturally exposed concrete, are formed with rough sawn lumber to give the formed surface a classic, board-formed appearance. Each form board was strategically located with variable dimensions (lengths and depth) to give the wall an undulating, acoustically roughened surface to disperse the sound.
- All floor areas within the Hall itself, including the seating area, stage and orchestra pit, were fitted with a floating concrete slab over an acoustic isolation mat. This system was installed directly on the parking structure “roof” slab, and exists as a walking surface in the crawlspace under the stage and seating area, and the finish floor surface at the orchestra pit.
- Corridors and ancillary spaces around the perimeter of the Hall are constructed with concrete topping slabs over acoustic underlayment.
- Seating area slab is a 10 inch thick flat slab, supported on interior concrete columns (stub columns bearing on the parking structure below) and the perimeter load bearing walls. To isolate this slab from structure-born noise and vibration, it is fully supported on three inch thick rubber bearing pads at all bearing locations (interior columns and perimeter walls).
- Seating area included a precast concrete ceiling. This ceiling is constructed using four inch thick, prestressed concrete panels that are supported from the bottom chord of the roof trusses. These panels not only provide the necessary acoustic separation, but also serve as the walking surface for maintenance of many theater systems that reside in the attic space.
UNIQUE STRUCTURAL AND/OR ARCHITECTURAL DESIGN FEATURES
The use of cast-in-place concrete framing was driven by a number of factors, the most prominent being concrete’s superb properties for acoustics and vibration control, and the fact that concrete framing is highly cost-effective in the Dallas market. The decision to expose much of the concrete framing in an architectural fashion was driven largely by budget constraints, but also due to the pleasing light gray appearing of Dallas area concrete, which was further enhanced with the addition of blast furnace slag.
ARCHITECTURALLY EXPOSED ELEMENTS:
- Exterior concrete walls: Exposed in an “as cast” condition with smooth formwork.
- Interior walls at the Hall: Exposed with articulated board forms at the sides and rear, with smooth board forms at the proscenium.
- Remaining interior walls: Exposed in an “as cast” condition with smooth formwork.
- Lobby stair, lobby upper level and balcony framing: Partially exposed beams and slabs.
- Lobby and ground floor corridors: Topping slab with ground and polished finish to expose the aggregate in the concrete matrix. (The resulting appearance is one similar to terrazzo.)
LOBBY STAIR FEATURE:
Cantilevering 15 feet from the interior lobby concrete wall, the lobby stair hovers above the main floor below. Like most of the structure, the stair is cast-in-place concrete, and is largely architecturally exposed. With a floor-to-floor height of 26 feet, the stair has three intermediate landings that cantilever from the 18-inch thick lobby wall. The cantilever is made possible by using 24-inch deep beams post-tensioned with high strength Dywidag bars anchored into the wall.
REASONS FOR CHOOSING REINFORCED CONCRETE
The use of reinforced concrete played a key role in realizing a sustainable and energy efficient building. The concrete mix used for the architecturally exposed walls and upper level floors included a high cementitious replacement of ground granulated blast furnace slag. In addition to providing a beneficial use of an industrial byproduct, it reduced the amount of cement required. Not only that, but the slag material resulted in concrete that was slightly lighter in color, a desirable effect.
The perimeter walls are 18 inch thick cast-in-place concrete. Energy modeling showed that, due to thermal mass properties, insulation was not required in the perimeter walls to exceed the energy goals for the project. LEED® Silver was required by the City of Dallas.